MFC r315112, r315196

r315112:
Add the capability to refresh the gpart(8) label without need a reboot.

gpart(8) has functionality to change the label of an GPT partition.
This functionality works like it should, however, after a label change
the /dev/gpt/ entries remain unchanged. glabel(8) status output remains
unchanged. The change only takes effect after a reboot.

PR:		162690
Submitted by:	sub.mesa@gmail, Ben RUBSON <ben.rubson@gmail.com>, ae
Reviewed by:	allanjude, bapt, bcr
Differential Revision:	https://reviews.freebsd.org/D9935

r315196:
After r315112 I broke the tests with eli, instead to pass 0, I should pass
M_NOWAIT to g_media_changed() that will call g_post_event() with this flag.

Reported by:	lwhsu, ngie and ae

2 files changed, 37 insertions, 1 deletions

diff --git a/sbin/geom/class/label/geom_label.c b/sbin/geom/class/label/geom_label.c
index 6c880ee..8a2f57c 100644
--- a/sbin/geom/class/label/geom_label.c
+++ b/sbin/geom/class/label/geom_label.c
@@ -53,6 +53,7 @@ static void label_main(struct gctl_req *req, unsigned flags);
 static void label_clear(struct gctl_req *req);
 static void label_dump(struct gctl_req *req);
 static void label_label(struct gctl_req *req);
+static void label_refresh(struct gctl_req *req);
 
 struct g_command PUBSYM(class_commands)[] = {
 	{ "clear", G_FLAG_VERBOSE, label_main, G_NULL_OPTS,
@@ -74,6 +75,9 @@ struct g_command PUBSYM(class_commands)[] = {
 	{ "label", G_FLAG_VERBOSE | G_FLAG_LOADKLD, label_main, G_NULL_OPTS,
 	    "[-v] name dev"
 	},
+	{ "refresh", 0, label_main, G_NULL_OPTS,
+	    "dev ..."
+	},
 	{ "stop", G_FLAG_VERBOSE, NULL,
 	    {
 		{ 'f', "force", NULL, G_TYPE_BOOL },
@@ -105,6 +109,8 @@ label_main(struct gctl_req *req, unsigned flags)
 		label_clear(req);
 	else if (strcmp(name, "dump") == 0)
 		label_dump(req);
+	else if (strcmp(name, "refresh") == 0)
+		label_refresh(req);
 	else
 		gctl_error(req, "Unknown command: %s.", name);
 }
@@ -223,3 +229,28 @@ label_dump(struct gctl_req *req)
 		printf("\n");
 	}
 }
+
+static void
+label_refresh(struct gctl_req *req)
+{
+	const char *name;
+	int i, nargs, fd;
+
+	nargs = gctl_get_int(req, "nargs");
+	if (nargs < 1) {
+		gctl_error(req, "Too few arguments.");
+		return;
+	}
+
+	for (i = 0; i < nargs; i++) {
+		name = gctl_get_ascii(req, "arg%d", i);
+		fd = g_open(name, 1);
+		if (fd == -1) {
+			printf("Can't refresh metadata from %s: %s.\n",
+			    name, strerror(errno));
+		} else {
+			printf("Metadata from %s refreshed.\n", name);
+			(void)g_close(fd);
+		}
+	}
+}
diff --git a/sbin/geom/class/label/glabel.8 b/sbin/geom/class/label/glabel.8
index a2f665e..c426a06 100644
--- a/sbin/geom/class/label/glabel.8
+++ b/sbin/geom/class/label/glabel.8
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd April 22, 2013
+.Dd March 12, 2017
 .Dt GLABEL 8
 .Os
 .Sh NAME
@@ -57,6 +57,9 @@
 .Cm dump
 .Ar dev ...
 .Nm
+.Cm refresh
+.Ar dev ...
+.Nm
 .Cm list
 .Nm
 .Cm status
@@ -186,6 +189,8 @@ Same as
 Clear metadata on the given devices.
 .It Cm dump
 Dump metadata stored on the given devices.
+.It Cm refresh
+Refresh / rediscover metadata from the given devices.
 .It Cm list
 See
 .Xr geom 8 .